The present invention relates to mining, in particularly longwall mining,
Longwall mining is one of three underground coal mining methods typically used. A seam of coal which can be suitably mined using longwall mining is typically 1 to 6 meters in thickness and may extend at an angle to the horizontal. To enable coal to be mined using the longwall method, a seam of coal is typically divided into a number of elongated rectangular blocks by forming a network of roads throughout the seam. The roads typically include a series of parallel roads. The roads are typically straight, although their height varies according to variation in thickness of the seam of coal, The roads are formed so that their height, where possible, is equivalent to or less than the thickness of the seam of coal.
Referring to FIG. 1, the network of roads typically includes roads A1 and B1 and a series of approximately parallel roads 1, 2, 3, 4 . . . n which are approximately normal to roads A1 and B1. Road A1 can include any number of adjacent, parallel roads and is formed first. Roads 1 and 2 are then developed and the development of road B1 usually follows the development of roads 1 and 2. The development of roads 3 and 4 are typically positioned close to each other as are roads 1 and 2. Roads 2 and 3 are typically separated by a much larger distance to define an elongated rectangular block of coal, namely block A of FIG. 1. Although the network of roads typically includes pairs of closely positioned, approximately parallel roads, 1 and 2, 3 and 4 etc, a network of roads can include a repeating pattern of up to 5 or more closely positioned, approximately parallel roads which are separated by a sufficient distance to span the width of Blocks A, B etc.
Block A is mined using a longwall shearer which repeats a cycle involving moving a small distance from road B1 (the top of Block A as viewed in FIG. 1) toward road A1, and subsequent lateral movement of a plough shear or rotatable cutting drum across the coal face which spans the width of Block A. As the shearer moves from road B1 toward road A1, it mines block A with the use of the plough shear or rotatable cutting drum which moves across coal face, cutting coal from the longwall face of block A. The separation distance of roads 2 and 3 is therefore determined by the maximum lateral movement of the longwall shearer.
Roads 1, 3, 5 etc are developed to provide alternative escape routes in the event of an emergency situation. The roads also deliver a continuous supply of air to dilute methane gas. The profile of roads 1, 3, 5 etc is typically the same as that of roads 2, 4 and 6. As can be seen from FIG. 1, roads 5 and 6 are spaced apart from roads 3 and 4 the same distance that roads 3 and 4 are spaced apart from 1 and 2 to create elongated rectangular block B, which has approximately the same width as elongated rectangular block A. The process of developing roads is repeated to create a series of adjacent elongated rectangular blocks.
Roads 1-n are typically formed using a Continuous Mining Machine (CMM) in combination with a Shuttle Car (SC) and a Conveyor Belt (CB). In the case of a series of pairs of roads, 1 and 2, 3 and 4 etc, as shown in FIG. 1, a pair of adjacent roads is usually developed together with a single CMM. The process of creating pairs of roads is typically the same for each pair of roads. For ease of explanation, roads 1 and 2 will be referred to throughout the specification; however, the reference 1 and 2 applies equally to any of the pairs of roads, 1 and 2, 3 and 4, 5 and 6 etc of FIG. 1 and also applies to a pair of adjacent roads which form part of a number of closely positioned, approximately parallel roads in road development systems that include more than one alternative escape route and air passageway. A conveyor belt (CB) is assembled in road 2 to extend along the longitudinal length of road 2 as it is being developed and hence extended by the CMM. Coal which is mined from the CMM is transferred to the CB by a SC. Each pair of roads is developed so that lateral roads link roads 1 and 2. The lateral roads are also formed by the CMM and are typically developed by mining, with the CMM, from road 2 to road 1. One method typically used to develop roads 1 and 2 and the lateral roads is as follows:
(a) The CMM mines road 2 so that it extends beyond the end of road 1 and a recently formed lateral road, with the SC making frequent trips between the CMM and the end of the conveyor.
(b) The CMM then retraces its path along road 2 until it reaches the most recently formed lateral road and moves to road 1 via this lateral road and subsequently mines road 1 so that its blind end is approximately laterally positioned relative to the blind end of road 2.
(c) The CMM then crosses over to road 2 to develop a lateral road which extends between blind ends of roads 1 and 2.
(d) The CMM then retraces its path along the most recently formed lateral road until it reaches road 2.
As the above cycle is repeated, an end of the CB which is closest to the CMM is moved along the length of road 2 to follow the CMM as it mines and hence extends road 2. However, the CB is not extended beyond a lateral hole until the next lateral hole is developed. The SC constantly moves between the CMM and the SB, as the CMM develops roads 1 and 2 and the lateral roads.
The efficiency and hence productivity of the CMM is greatly reduced by any movement of the CMM in the above described steps a-d which is not for the purpose of extending roads 1 or 2 or the lateral roads. That is, any movement between roads 1, 2 or the lateral roads, as well as any movement which requires the CMM to retrace its path, has a substantial negative impact on the productivity of the CMM. Because the productivity of longwall mining is limited by the speed with which the roads are created, it is desirable to provide a more efficient method of roadway development for longwall mining. It is therefore also desirable to provide apparatus suitable for implementing an improved method of roadway development.
It is the object of the present invention to overcome or substantially ameliorate at least one of the above disadvantages.
The present invention provides a method of roadway development for longwall mining comprising the steps of:
(a) developing first and second substantially parallel roads;
(b) joining first and second roads with lateral tunnels which extend laterally between the first and second roads and are positioned at predetermined distances along the longitudinal length of the first and second roads; and
(c) transporting material mined in the process of developing the first road to the second road, via one of the lateral tunnels for transportation along the second road and subsequently out of the mine.
The step of joining the first and second roads with lateral tunnels preferably comprises the steps of:
(a) forming a blind hole which extends laterally from the second road; and
(b) extending the first road to intersect a blind end of the blind hole to result in the lateral road joining the first and second roads.
The second road is therefore preferably developed ahead of the first road so that lateral tunnels, which extend from the second road, do not intersect the first road until the first road is subsequently developed or extended. The subsequent development of the first road results in the first road intersecting a recently formed lateral tunnel. The material mined in the process of developing the-first road is preferably transported, via a lateral tunnel which is closest to an end of the first road which is being mined. An auger which may be used to transport material which is mined in the process of developing the first road, to the second road is therefore preferably moved along the first road in the direction in which the first road is being developed or extended, to more recently developed lateral tunnels which are closer to the end of the first road which is being mined. However, the auger cannot be moved to a more recently developed lateral tunnel until the first road has been extended sufficiently beyond the more recently developed lateral tunnel to permit both the equipment which is being used to develop the first road and the auger to be appropriately positioned along the first road.
The step of developing the first and second roads preferably comprises independently developing the first and second roads with independent mining equipment.
The blind holes arc preferably formed with the use of an auger or drill.
The material mined from the first road is preferably transported to the second road via an auger.
Independent continuous mining machines (CMM) may be used to develop the first and second roads. Material mined in the process of developing the first road may be transported to the auger via a shuttle car. Material mined in the process of developing the second road is preferably transported out of the mine via a conveyor which extends down the length of the second road. The conveyor is preferably periodically extended to extend along the length of the second road as the second road is developed. The material transported from the first road to the second road, via the auger, is preferably deposited onto the conveyor.
Movable conveyor means may be used to transport material which is mined in the process of developing the second road to the conveyor. The movable conveyor means may comprise a movable conveyor, one end of which is fixed relative to the mining equipment which develops the second road and the other end of which is movable relative to the conveyor, the movable conveyor being positioned above the conveyor and adapted to extend along part of the length of the conveyor which is proximal the end of the second road which is being mined, so that movement of the movable conveyor along the second road with development of the second road results in movement of the movable conveyer relative to the conveyer and the depositing of mined material from a depositing end of the movable conveyor onto the conveyer. When the depositing end of the movable conveyor approaches the end of the conveyor which is proximal the end of the second road which is being mined, the conveyor is extended along the second road which is being mined, and the movable conveyor is repositioned along the length of the conveyor to enable the movable conveyor to again be moved along the second road while depositing mined material, via the depositing end of the movable conveyor, onto the conveyor.
The auger which may be used to transport material which is mined in the process of developing the first road, to the second road, may be substantially equivalent to the drill or auger which is used to form the lateral tunnels.
The present invention in a preferred form also provides movable conveyor means having a first portion which is arranged to receive material which has been mined by mining equipment which develops underground roadways, and a second portion which is arranged for movement relative to a stationary conveyor and depositing of a mined material received from the mining equipment onto a surface of the stationary conveyor which is adapted to convey material along the longitudinal length of the stationary conveyor.
The movable conveyor means may comprise a chain and/or belt conveyor(s) having a longitudinal axis which is arranged for substantial alignment with the longitudinal axis of the stationary conveyor wherein the conveyor is arranged for movement relative to the stationary conveyor in a direction which is substantially aligned with the longitudinal axis of the conveyor. The first and second portions of the movable conveyor means may comprise first and second ends respectively of a conveyor or two or more associated conveyors which are arranged to move relative to a stationary conveyor upon movement of mining equipment. The mining equipment may comprise a continuous mining machine (CMM) and an associated drill or auger which is adapted to drill holes laterally relative to a road which the CMM is developing.
The present invention in a preferred form also provides a drill or auger apparatus comprising a drill or auger string respectively, pumping means for pumping a gas, and transport means for transporting the pumped gas to a blind end of a hole which is being drilled by the drill or auger string, wherein the pumping means, in combination with the transport means, is adapted to pump a gas from a driven end of the drill or auger string, via the transport means, to a blind end of the hole.
The drill or auger string may comprise hollow stem auger flights and an associated cutter head wherein the pumping means, in combination with the hollow stem auger flights, is adapted to pump a gas from a driven end of the hollow stem auger flights, through the hollow stem of the hollow stem auger flights, and out of the hollow stem at an end of the hollow stem which is proximal the cutter head.
The pumping means may be adapted to pump air to the cutter head end of hollow stem auger flights for the purpose of diluting methane gas to non explosive levels.
The apparatus may further include gas detection means for detecting the levels of methane gas at an end of a hole which is drilled by the apparatus which is adjacent the driven end of the apparatus.
The gas detection means may be adapted to automatically shut down the drill or auger apparatus if the gas detection means detects hazardous levels of methane. The gas detection means may comprise a methanomitor.
The pumping means preferably comprises a pump which is attached to a hollow stem of the hollow stem auger flights, via sealing means. The sealing means may comprise a seal which is adapted to seal two rotatably engagable members.
A further method is disclosed herein, the method being a method of roadway development for longwall mining comprising:
(a) developing a first road by use of a first continuous mining machine;
(b) delivering mined material from the first machine to a first longitudinally extendable first conveyor extending rearwardly from the first machine;
(c) delivering the material from the first conveyor to a second conveyor via which mined material from the first road is delivered from the first road;
(d) developing a second road by use of a second continuous timing machine, the second road being substantially parallel to the first road;
(e) delivering the mined material from the second machine to a longitudinally extendable third conveyor extending rearwardly from the second machine,
(f) delivering the mined material from the third conveyor to a transverse auger conveyor extending between the first and second roads so that mined material from the third conveyor is delivered to the second conveyor.
In a modification of the above method, a shuttle car conveys material from the second continuous miner to the third conveyor.
In a further modified form of the above method, the third conveyor is replaced with a shuttle car that conveys material from the second continuous miner to the auger conveyor.
In a still modified form of the above method, the first conveyor is replaced with a shuttle car that conveys material from the first continuous miner to be delivered to the second conveyor.
In the above described methods preferably the auger conveyor is provided by an auger mining machine via which material is conveyed to the second conveyor and to which mined material is delivered from the first and second mining machines.
There is still further disclosed herein a method of roadway development for longwall mining comprising:
(a) developing a first road by use of a first continuous mining machine;
(b) delivering mined material from the first machine to a first conveyor;
(c) developing a second road by use of a second continuous mining machine, the second road being substantially parallel to the first road;
(d) delivering mined material from the second mining machine by an auger conveyor to said first conveyor; and
(e) the material from said second mining machine being delivered to said auger conveyor by means of a shuttle car.
Preferably in the above method the auger conveyor is provided by an auger mining machine, to which material from said first machine is directly delivered to be conveyed to said first conveyor.
In the preceeding summary of the invention, except where the context requires otherwise, due to express language or necessary implications, the words xe2x80x9ccomprisingxe2x80x9d, xe2x80x9ccomprisesxe2x80x9d, or xe2x80x9ccomprisexe2x80x9d are used in the sense of xe2x80x9cincludingxe2x80x9d, that is the features specified may be associated with further features in various embodiments of the invention.